3GPP specifies the 3rd generation (3G) LTE as a part e.g. of Release 8 of the 3GPP specifications. A subsequent release of LTE (LTE, e.g. Release 9) and possibly Release 8 may support both closed subscribed group cells (CSG, also known as Home evolved Node Bs (eNBs)) and non-CSG cells (also known as macro cells). Also, user equipments (UEs) (e.g. terminals) may be categorized according to the CSG and non-CSG division, i.e. some terminals may obtain access to both macro cells and CSG cells, while some other terminals do not possess the capability to access CSG cells.
Since some UE procedures (e.g. like mobility or cell identification etc.) may depend on the type of the accessed cell (accessed e.g. via cell selection or cell reselection or handover), and since some UEs may not be capable of accessing a CSG cell, it is applicable that the UEs may distinguish between CSG and non-CSG cells.
Furthermore, it could be avoided that UEs incapable of CSG or UEs which are not registered to any CSG cell, like a H(e)NB, may yield increased power consumption due to the fact that CSG cells are deployed e.g. in the same frequency band where also macro (e)NBs may be operated. This may e.g. be the case if UEs detect that a cell has restricted access very late during idle mode measurement procedures, like cell selection or cell reselection, and also in connected mode during handover.
A worst case scenario may be for example if a UE incapable of CSG travels along a road comprising houses with H(e)NBs on both sides. Then, if there is no early indication that these cells are not relevant for handover or for camping, then the UE's power consumption may increase dramatically compared to the case where the UE detects early that all these cells are home cells where access is not permitted.
There have been approaches addressing the above drawbacks.
One such approach (see e.g. 3GPP radio access network (RAN) working group 2 (WG2)) to distinguish between CSG and non-CSG cells may reside in including a CSG flag (i.e. 1 bit) in the broadcast control channel (BCCH) of each cell, e.g. over downlink shared channel/physical downlink shared channel (DL-SCH/PDSCH).
A possible drawback of the above approaches may reside in that, in order to indentify a cell type, the UE may have to execute the whole cell search (PSS and SSS detection), then demodulate/decode the physical broadcast channel (PBCH) and finally demodulate/decode the BCCH, e.g. if CSG information is coded in BCCH system information and the cell is then found to be inapplicable. If a reserved range of physical layer cell IDs is transmitted in BCCH system information, the UE may have to decode the BCCH at least once.
A further possible drawback may reside in that the above procedure may introduce additional UE power consumption and delay before the cell type is identified even for the UEs incapable of accessing CSG cells. A still further possible drawback may reside in that, by limiting the number of physical cell IDs for macro cells with no access restrictions (non-CSG cells), network planning becomes more difficult for an operator.
A still further possible drawback may reside in that, by limiting the number of physical cell IDs for CSG cells with access restrictions, Configuration of theses cells may become difficult, in particular if a really large number of such cells is set up in a small area.
In consideration of the above, it is an object of examples of the present invention to overcome one or more of the above drawbacks. In particular, the present invention provides methods, apparatuses, a system and a related computer program product for cell type detection.
According to an example of the present invention, in a first aspect, this object is for example achieved by a method comprising:
transmitting signaling information subjected to one of modulation by at least one predefined phase modulation and scrambling by at least one predefined scrambling sequence, the one of the modulation and scrambling being indicative of network cells of a first type and network cells of a second type different from the first type.
According to further refinements of the example of the present invention as defined under the above first aspect,
the method further comprises subjecting the signaling information to the one of modulation and scrambling;
the method further comprises modulating the signaling information by the at least one predefined phase modulation;
the method further comprises scrambling the signaling information by the at least one predefined scrambling sequence;
the method further comprises assigning a set of synchronization information to a subset of the network cells, wherein the signaling information is subjected to the one of the modulation and scrambling only for the subset of the network cells;
the method further comprises signaling control information, wherein the transmitting is performed as an auxiliary indication to the signaling.
According to an example of the present invention, in a second aspect, this object is for example achieved by a method comprising:
transmitting one of the following:                i) a primary synchronization signal and a reference signal, the primary synchronization signal and the reference signal having at least one predefined phase relation to each other,        ii) a secondary synchronization signal and a reference signal, the secondary synchronization signal and the reference signal having at least one predefined phase relation to each other, or        iii) a primary synchronization signal and a secondary synchronization signal, the primary synchronization signal and the secondary synchronization signal having at least one predefined phase relation to each other,the at least one phase relation being indicative of network cells of a first type and network cells of a second type different from the first type.        
According to an example of the present invention, in a third aspect, this object is for example achieved by a method comprising:
transmitting indication information indicating network cells of a first type, the network cells being different from network cells of a second type, the transmitting comprising at least one of the following:
a) broadcasting control information, the indication information to be transmitted being an indication flag;
b) assigning a set of synchronization information to the network cells of the first type, and broadcasting control information, the indication information to be transmitted being the synchronization information;
c) reserving at least one signaling code information for the network cells of the first type, the indication information to be transmitted being the signaling code information;
d) transmitting according to the above first aspect; and
e) transmitting according to the above second aspect.
According to further refinements of the example of the present invention as defined under the above third aspect,
the transmitting of indication information is based on a number of network cell identities for the network cells of the first type, a first number of network cell identities for the network cells of the first type and a second number of network cell identities for the network cells of the first type, the number and the first and second numbers being integers equal to or greater than one, the second number being greater than the first number, wherein the transmitting of item a) is performed if the number is substantially equal to zero, the transmitting of item b) is performed if the number is significantly smaller than the first number, the transmitting of item c) is performed if the number is substantially smaller than the first number or if the number is greater than the first number and smaller than the second number, the transmitting of item d) is performed if the number is greater than the second number, and the transmitting of item e) is performed if the number is greater than the second number;
the transmitting of item a) is also performed if a number of terminals of the first type substantially reaches the number of all available terminals;
the transmitting of item b) is performed for a subset of the network cells, if the number is greater than the first number and smaller than the second number;
the transmitting of item c) is performed if the number is substantially smaller then the second number.
According to further refinements of the example of the present invention as defined under the above first to third aspects,
the method further comprises signaling scheme information on a scheme to be used.
According to an example of the present invention, in a fourth aspect, this object is for example achieved by a method comprising:
detecting network cells of a first type and network cells of a second type different from the first type based on received signaling information subjected to one of modulation by at least one predefined phase modulation and scrambling by at least one predefined scrambling sequence, the one of the modulation and scrambling being indicative of the network cells of the first type and the network cells of the second type.
According to further refinements of the example of the present invention as defined under the above fourth aspect,
the method further comprises demodulating the signaling information by the at least one predefined phase modulation;
the method further comprises descrambling the signaling information by the at least one predefined scrambling sequence;
the method further comprises receiving the signaling information;
the detecting further comprises testing the received signaling information against a hypothesis;
the method further comprises dereferencing, from a set of synchronization information, a subset of the network cells, wherein the signaling information is subjected to one of demodulation and descrambling only for the subset of the network cells;
the method further comprises receiving signaled control information, wherein the detecting is performed based on the received control information and on the received signaling information as an auxiliary indication.
According to an example of the present invention, in a fifth aspect, this object is for example achieved by a method comprising:
detecting network cells of a first type and network cells of a second type different from the first type based on receiving one of the following:                i) a primary synchronization signal and a reference signal, the primary synchronization signal and the reference signal having at least one predefined phase relation to each other,        ii) a secondary synchronization signal and a reference signal, the secondary synchronization signal and the reference signal having at least one predefined phase relation to each other, or        iii) a secondary synchronization signal and a primary synchronization signal, the primary synchronization signal and the secondary synchronization signal having at least one predefined phase relation to each other,the at least one phase relation being indicative of network cells of a first type and network cells of a second type different from the first type.        
According to an example of the present invention, in a sixth aspect, this object is for example achieved by a method comprising:
detecting network cells of a first type and network cells of a second type different from the first type based on received indication information indicating the network cells of the first type, the detecting comprising at least one of the following:
a) receiving broadcasted control information, and the indication information received being an indication flag;
b) dereferencing, from a set of synchronization information, the network cells of the first type, and receiving broadcasted control information, the indication information received being the synchronization information;
c) reserving at least one signaling code information for the network cells of the first type, the indication information received being the signaling code information;
d) receiving according to the above fourth aspect; and
e) receiving according to the above fifth aspect.
According to further refinements of the example of the present invention as defined under the above fourth to sixth aspects,
the method further comprises receiving signaled scheme information on a scheme used, wherein the detecting is performed based on the signaled scheme to be used.
According to further refinements of the example of the present invention as defined under the above first to sixth aspects,
the signaling information is constituted by a reference signal;
the network cells of the first type are constituted by closed subscriber group network cells;
the network cells of the second type are constituted by one of non-closed subscriber group network cells and macro cells;
the set of synchronization information is constituted by pairs of a primary synchronization signal and a secondary synchronization signal;
the control information is constituted by a one of a broadcast control channel and a primary broadcast channel;
the first number is 168;
the second number is one of 337 and 504;
the indication flag is constituted by a closed subscriber group flag;
the signaling code information is constituted by a primary synchronization signal code.
According to an example of the present invention, in a seventh aspect, this object is for example achieved by an apparatus comprising:
means for transmitting signaling information subjected to one of modulation by at least one predefined phase modulation and scrambling by at least one predefined scrambling sequence, the one of the modulation and scrambling being indicative of network cells of a first type and network cells of a second type different from the first type.
According to further refinements of the example of the present invention as defined under the above seventh aspect,
the apparatus further comprises means for subjecting the signaling information to the one of modulation and scrambling;
the apparatus further comprises means for modulating the signaling information by the at least one predefined phase modulation;
the apparatus further comprises means for scrambling the signaling information by the at least one predefined scrambling sequence;
the apparatus further comprises means for assigning a set of synchronization information to a subset of the network cells, wherein the means for subjecting is configured to subject the signaling information to the one of the modulation and scrambling only for the subset of the network cells;
the apparatus further comprises means for signaling control information, wherein the means for transmitting is configured to transmit as an auxiliary indication to the signaling performed by the means for signaling.
According to an example of the present invention, in an eighth aspect, this object is for example achieved by an apparatus comprising:
means for transmitting one of the following:                i) a primary synchronization signal and a reference signal, the primary synchronization signal and the reference signal having at least one predefined phase relation to each other,        ii) a secondary synchronization signal and a reference signal, the secondary synchronization signal and the reference signal having at least one predefined phase relation to each other, or        iii) a primary synchronization signal and a secondary synchronization signal, the primary synchronization signal and the secondary synchronization signal having at least one predefined phase relation to each other,the at least one phase relation being indicative of network cells of a first type and network cells of a second type different from the first type.        
According to an example of the present invention, in a ninth aspect, this object is for example achieved by an apparatus comprising:
means for transmitting indication information indicating network cells of a first type, the network cells being different from network cells of a second type, the means for transmitting further comprising at least one of the following:
a) means for broadcasting control information, the indication information to be transmitted being an indication flag;
b) means for assigning a set of synchronization information to the network cells of the first type, and means for broadcasting control information, the indication information to be transmitted being the synchronization information;
c) means for reserving at least one signaling code information for the network cells of the first type, the indication information to be transmitted being the signaling code information;
d) means for transmitting according to the above seventh aspect; and
e) means for transmitting according to the above eighth aspect.
According to further refinements of the example of the present invention as defined under the above ninth aspect,
the means for transmitting of indication information is configured to transmit based on a number of network cell identities for the network cells of the first type, a first number of network cell identities for the network cells of the first type and a second number of network cell identities for the network cells of the first type, the number and the first and second numbers being integers equal to or greater than one, the second number being greater than the first number, wherein the means for transmitting comprises at least one of the following the means of item a) if the number is substantially equal to zero, the means of item b) if the number is significantly smaller than the first number, the means of item c) if the number is substantially smaller than the first number or if the number is greater than the first number and smaller than the second number, the means of item d) if the number is greater than the second number, and the means of item e) if the number is greater than the second number;
the means for transmitting of item a) is configured to transmit also if a number of terminals of the first type substantially reaches the number of all available terminals;
the means for transmitting of item b) is configured to transmit for a subset of the network cells, if the number is greater than the first number and smaller than the second number;
the means for transmitting of item c) is configured to transmit if the number is substantially smaller then the second number.
According to further refinements of the example of the present invention as defined under the above seventh to ninth aspects,
the apparatus further comprises means for signaling scheme information on a scheme to be used.
According to an example of the present invention, in a tenth aspect, this object is for example achieved by an apparatus comprising:
means for detecting network cells of a first type and network cells of a second type different from the first type based on received signaling information subjected to one of modulation by at least one predefined phase modulation and scrambling by at least one predefined scrambling sequence, the one of the modulation and scrambling being indicative of the network cells of the first type and the network cells of the second type.
According to further refinements of the example of the present invention as defined under the above seventh to tenth aspect,
the apparatus further comprises means for demodulating the signaling information by the at least one predefined phase modulation;
the apparatus further comprises means for descrambling the signaling information by the at least one predefined scrambling sequence;
the apparatus further comprises means for receiving the signaling information;
the means for detecting further comprises means for testing the received signaling information against a hypothesis;
the apparatus further comprises means for dereferencing, from a set of synchronization information, a subset of the network cells, wherein the one of the means for demodulating and the means for descrambling the signaling information is configured to demodulate or descramble only for the subset of the network cells;
the apparatus further comprises means for receiving signaled control information, wherein the means for detecting is configured to detect based on the control information received by the second means for receiving and on the signaling information received by the means for receiving as an auxiliary indication.
According to an example of the present invention, in an eleventh aspect, this object is for example achieved by an apparatus comprising:
means for detecting network cells of a first type and network cells of a second type different from the first type based on receiving, by means for receiving, one of the following:                i) a primary synchronization signal and a reference signal, the primary synchronization signal and the reference signal having at least one predefined phase relation to each other,        ii) a secondary synchronization signal and a reference signal, the secondary synchronization signal and the reference signal having at least one predefined phase relation to each other, or        iii) a primary synchronization signal and a secondary synchronization signal, the primary synchronization signal and the secondary synchronization signal having at least one predefined phase relation to each other,the at least one phase relation being indicative of the network cells of the first type and the network cells of the second type.        
According to an example of the present invention, in a twelfth aspect, this object is for example achieved by an apparatus comprising:
means for detecting network cells of a first type and network cells of a second type different from the first type based on received indication information indicating the network cells of the first type, the means for detecting comprising at least one of the following:
a) the indication information received being an indication flag;
b) means for dereferencing, from a set of synchronization information, the network cells of the first type, and means for receiving broadcasted control information (BCCH), the indication information received being the synchronization information;
c) means for reserving at least one signaling code information for the network cells of the first type, the indication information received being the signaling code information;
d) means for receiving according to the above tenth aspect; and e) means for receiving according to the above eleventh aspect.
According to further refinements of the example of the present invention as defined under the above seventh to twelfth aspects,
the signaling information is constituted by a reference signal;
the network cells of the first type are constituted by closed subscriber group network cells;
the network cells of the second type are constituted by one of non-closed subscriber group network cells and macro cells;
the set of synchronization information is constituted by pairs of a primary synchronization signal and a secondary synchronization signal;
the control information is constituted by a one of a broadcast control channel and a primary broadcast channel;
the first number is 168;
the second number is one of 337 and 504;
the indication flag is constituted by a closed subscriber group flag;
the signaling code information is constituted by a primary synchronization signal code;
at least one, or more of means for transmitting, means for subjecting, means for modulating, means for scrambling, means for assigning, means for signaling, means for detecting, means for demodulating, means for descrambling, means for dereferencing, means for receiving, means for testing and the apparatus is implemented as a chipset or module.
According to further refinements of the example of the present invention as defined under the above seventh to ninth aspects,
the apparatus is constituted by a one of a home evolved node B and a macro cell node B.
According to further refinements of the example of the present invention as defined under the above tenth to twelfth aspects,
the apparatus further comprises means for receiving signaled scheme information on a scheme used, wherein the means for detecting is configured to detect based on the signaled scheme to be used;
the apparatus is constituted by a user equipment.
According to an example of the present invention, in a thirteenth aspect, this object is for example achieved by a system comprising:
at least one home evolved node B according to the above seventh to ninth aspects; and
a user equipment according to the above tenth to twelfth aspects.
According to an example of the present invention, in a fourteenth aspect, this object is for example achieved by a computer program product comprising code means for performing method steps of a method according to the above first to sixth aspects, when run on a processing means or module.
In this connection, it has to be pointed out that examples of the present invention enable one or more of the following:
Providing an efficient and flexible method/apparatus for distinguishing between CSG cells and macro cells;
Enabling conveyance over wide area cells e.g. via the BCCH;
Early indication of CSG, e.g. if an operator deploys CSG nodes in the same carrier frequency as the macro deployment (which is open for all subscribers/UEs);
Eliminating the need to restrict the number of applicable physical cell IDs for non-CSG cells;
Eliminating the need to restrict the number of applicable physical cell IDs for CSG cells;
for the UE, eliminating the necessity for hardware changes and alleviating the necessity for big software changes;
Enabling CSG detection early during the cell search and neighbor cell measurement phase with minimal complexity;
Providing flexibility for an operator with respect to the number of deployed CSG cells. In case the number of CSG cells is large, a cell type may be detected already in first cell search step (e.g. scheme 1 described herein below), thus minimizing the negative impact of CSG cells to non-CSG UEs. Contrary, if the number of CSG cells is quite low, there is no need to reserve SSS and/or PSS codes, thus simplifying network planning for the operator.
For the network/(e)NB(s), eliminating reduction of the number of cell IDs for macro cells (and thus allowing also the same maximum number of cell IDs for CSG cells).
Eliminating additional UE power consumption and delay before the cell type is identified e.g. for the UEs incapable of accessing CSG cells.